共查询到20条相似文献,搜索用时 656 毫秒
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M. Ludvigsen 《General Relativity and Gravitation》1975,6(2):165-173
A twisting shear free solution of Maxwell's equations is obtained by transforming to a complex coordinate system in which the corresponding solution is complex but twist free. The equations in this system are easily solved, and, by transforming back to the original coordinates, a twisting shear free solution of Maxwell's equations is obtained. 相似文献
3.
In this paper, the Maxwell's equations are written as Hamilton canonical equations by using Hamilton functional variation method. Maxwell's equations can be discretized with symplectic propagation technique combined with high-order difference schemes approximations to construct symplectic finite difference time domain (SFDTD) method. The high-order dispersion equations of the scheme for space is deduced. The numerical dispersion analysis is included, and it is compared with the multiresolution time-domain (MRTD) method based on the Daubechies scaling functions. Numerical results show high efficiency and accuracy of the SFDTD method. 相似文献
4.
Sameer Ismail Farahat 《Fortschritte der Physik》1994,42(8):707-724
In classical physics the electromagnetic equations are described by Maxwell's equations. Maxwell's equations proved to be invariant under gauge, or Lorentz transformations. Also, Einstein's equations of the special theory of relativity are invariant under Lorentz transformations. On the other hand classical mechanics and quantum mechanics laws are invariant under Galilean transformations. This means that, there are two different dynamical structures describing our universe. Einstein's unified field theory failled in putting our universe in one dynamical structure. New electromagnetic and force field equations are going to be derived. They have the same shape like Maxwell's equations, but with different dynamical structure. Those equations are invariant under Galilean transformations and in the density matrix formalism of quantum mechanics. 相似文献
5.
《Comptes Rendus Physique》2016,17(10):1130-1138
We review recent progress in making the former gedanken experiments of Maxwell's demon [1] into real experiments in a lab. In particular, we focus on realizations based on single-electron tunneling in electronic circuits. We first present how stochastic thermodynamics can be investigated in these circuits. Next we review recent experiments on an electron-based Szilard engine. Finally, we report on experiments on single-electron tunneling-based cooling, overviewing the recent realization of a Coulomb gap refrigerator, as well as an autonomous Maxwell's demon. 相似文献
6.
David Lovelock 《General Relativity and Gravitation》1974,5(4):399-408
The most general Lagrange density (which is a concomitant of the metric tensor together with a vector field and its first derivatives) for which the associated Euler-Lagrange equations are precisely Maxwell's equations is obtained. Although it is more general than the Lagrangian which is commonly used, it still has essentially the same energy momentum tensor. 相似文献
7.
Jack Cohn 《International Journal of Theoretical Physics》1974,9(3):179-184
A relativistic, non-quantum theory of electrons is constructed in which the electron is not considered to be composed of any type of distribution of charge. The electron's structurelessness is defined by several assumptions which, together with Maxwell's equations outside the electron, yield the general fields produced by such an arbitrarily movingholistic electron. Several equations of motion for the holistic electron are found to result from the formulation, the Lorentz-Dirac equation being among them. The formulation, by its very nature, avoids the problems of the electron self-energy and the need for normalization. 相似文献
8.
Posteriori Error Estimation for an Interior Penalty Discontinuous Galerkin Method for Maxwell's Equations in Cold Plasma
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Jichun Li 《advances in applied mathematics and mechanics.》2009,1(1):107-124
In this paper, we develop a residual-based a posteriori error
estimator for the time-dependent Maxwell's equations in the cold
plasma. Here we consider a semi-discrete interior penalty
discontinuous Galerkin (DG) method for solving the governing
equations. We provide both the upper bound and lower bound analysis
for the error estimator. This is the first posteriori error analysis
carried out for the Maxwell's equations in dispersive media. 相似文献
9.
J. M. Hobbs 《International Journal of Theoretical Physics》1974,9(3):157-165
It is shown that the action of the usual field theory requires the inclusion of two terms in order to be equivalent, in the macroscopic case, to the action proposed by Hoyle & Narlikar (1964c). These actions correspond only to a modified form of Maxwell's equations, which, in consequence, lose their property of conformal invariance. It is also demonstrated how theC-field and electromagnetic field can be brought into unison by an appropriate re-definition of the vector potential. Both field theories can thus be described in terms of one vector Green's function. 相似文献
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Jiangxing Wang Ziqing Xie & Chuanmiao Chen 《advances in applied mathematics and mechanics.》2015,7(6):796-817
An implicit discontinuous Galerkin method is introduced to solve the time-domain
Maxwell's equations in metamaterials. The Maxwell's equations in metamaterials
are represented by integral-differential equations. Our scheme is based on discontinuous
Galerkin method in spatial domain and Crank-Nicolson method in temporal
domain. The fully discrete numerical scheme is proved to be unconditionally stable.
When polynomial of degree at most $p$ is used for spatial approximation, our scheme is
verified to converge at a rate of $\mathcal{O}(τ^2+h^{p+1/2})$. Numerical results in both 2D and 3D
are provided to validate our theoretical prediction. 相似文献
12.
Dexter J. Booth 《International Journal of Theoretical Physics》1975,14(1):67-72
By distinguishing between the metric of a Riemannian geometry and the interval defining function it is demonstrated that both Einstein's gravitational field equations and Maxwell's electromagnetic field equations can be generated from a single geometry. 相似文献
13.
Numerical Simulation of a Multi-Frequency Resistivity Logging-While-Drilling Tool Using a Highly Accurate and Adaptive Higher-Order Finite Element Method
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Zhonghua Ma Dejun Liu Hui Li & Xinsheng Gao 《advances in applied mathematics and mechanics.》2012,4(4):439-453
A novel, highly efficient and accurate adaptive higher-order finite element
method ($hp$-FEM) is used to simulate a multi-frequency resistivity logging-while-drilling (LWD)
tool response in a borehole environment. Presented in this study are the vector expression
of Maxwell's equations, three kinds of boundary conditions, stability weak formulation of
Maxwell's equations, and automatic $hp$-adaptivity strategy. The new $hp$-FEM can select
optimal refinement and calculation strategies based on the practical formation model and
error estimation. Numerical experiments show that the new $hp$-FEM has an exponential
convergence rate in terms of relative error in a user-prescribed quantity of interest
against the degrees of freedom, which provides more accurate results than those obtained
using the adaptive $h$-FEM. The numerical results illustrate the high efficiency and
accuracy of the method at a given LWD tool structure and parameters in different physical
models, which further confirm the accuracy of the results using the Hermes
library (http://hpfem.org/hermes) with a multi-frequency resistivity LWD tool
response in a borehole environment. 相似文献
14.
V. Wünsch 《Annalen der Physik》1989,501(8):593-597
Generalizing the recently by J. Carminati and R. McLenaghan [2] obtained results it is shown that there exist no Petrov type D space-times on which the conformally invariant scalar wave equation, or Maxwell's equations, or Weyl's equations satisfy Huygens' principle. 相似文献
15.
《Physics letters. A》1987,122(8):397-398
Maxwell's electromagnetic equations are derived from Fermat's principle in geometrical optics by the process of “wavization” analogous to quantization of classical mechanics. 相似文献
16.
A High-Order Discontinuous Galerkin Method for the Two-Dimensional Time-Domain Maxwell's Equations on Curved Mesh
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Hongqiang Lu Yida Xu Yukun Gao Wanglong Qin & Qiang Sun 《advances in applied mathematics and mechanics.》2016,8(1):104-116
In this paper, a DG (Discontinuous Galerkin) method which has been widely
employed in CFD (Computational Fluid Dynamics) is used to solve the two-dimensional
time-domain Maxwell's equations for complex geometries on unstructured
mesh. The element interfaces on solid boundary are treated in both curved way
and straight way. Numerical tests are performed for both benchmark problems and
complex cases with varying orders on a series of grids, where the high-order convergence
in accuracy can be observed. Both the curved and the straight solid boundary
implementation can give accurate RCS (Radar Cross-Section) results with sufficiently
small mesh size, but the curved solid boundary implementation can significantly
improve the accuracy when using relatively large mesh size. More importantly, this
CFD-based high-order DG method for the Maxwell's equations is very suitable for
complex geometries. 相似文献
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Yu. G. Pavlenko 《Russian Physics Journal》1983,26(8):716-720
The solutions of Maxwell's equations in the parabolic equation approximation is obtained on the basis of the canonical transformation method. The Hamiltonian form of the equations for the field in an anisotropic stratified medium is also examined. The perturbation theory for the calculation of the wave reflection and transmission coefficients is developed. 相似文献
19.
《Physics letters. A》1997,234(2):75-85
The experimental discovery by Dufour and Prunier that the Sagnac fringe displacement does not change when the source and fringe detector are locally transferred from the rotating platform to the laboratory frame is interpreted as a natural result of general relativity theory when one introduces non-zero mass photons into the theory of light. It also yields a proof of the reality of Langevin's paradox as a natural consequence of assuming that non-zero mass photons (1) follow real space-time paths, (2) are associated with real physical internal clock-like motions, (3) imply the existence of an absolute local inertial frame Σ0 first associated by Lorentz with Maxwell's equations. 相似文献
20.
G. Lessner 《General Relativity and Gravitation》1974,5(6):699-714
In the projective theory of relativity the 5-dimensional field equation \(_{\mu \nu } \) and the resulting equation of motion Tμυ;μ = 0 are investigated. There Tμυ stands for the 5-dimensional tensor of macroscopic matter. The 4-dimensional field equations and equation of motion obtained by projection are a generalization of Einstein's theory of general relativity and Maxwell's electrodynamics, involving a scalar field φ.They contain a single constant φ0.The weak field approximation is investigated for the case of an ideal fluid and leads to Newton's mechanics, including Newton's gravitational law, and to Maxwell's electrodynamics. For the constant φ0 one obtains the approximate value φ0c4/γN with Newton's gravitational constant γN.For homogeneous and isotropic cosmological models consisting of matter only the general solution for the radius K of curvature is given. This solution is independent of the equation of state of matter For a pure dust universe the general solution for the scalar field φ is given. For a closed universe a power law φ ?K?1 is valid which leads to Mach's principle. The calculation of the age of a closed universe yields over 7×109y,if one uses mean values of the present cosmological data. 相似文献